MSR's SweetWater Purifier System gives you added protection against bacteria, protozoa, and viruses. This backcountry kit includes a SweetWater Microfilter, an 80-micron stainless-steel prefilter, two color-coded silicone hoses, foam float, Universal Bottle Adapter plus cleanside cover, cleaning brush, ViralStop Purifier Solution and stuff sack. Simply pump the water through the SweetWater purifier, then add five drops of the purifier solution per liter and wait five minutes for the purification process to complete. MSR's water Purifier Solution inactivates 99.99 percent of waterborne viruses, bacteria, and common protozoan parasites, so you can avoid spending your camping or traveling expedition doubled over in your tent.